How to Fill a Hot Tub

Fill your backyard oasis to get jets and bubbles flowing

Close-up of a filled with water hot tub
Photo: ruizluquepaz / E+ / Getty Images
Close-up of a filled with water hot tub
Photo: ruizluquepaz / E+ / Getty Images
Stacey L. Nash
Written by Stacey L. Nash
Contributing Writer
Updated February 19, 2024

Difficulty

Easy

No experience? No problem.

Time to complete

4 hours

Time depends on water pressure.

Cost

$100–$500

This DIY is a no-brainer if you already own the tools.

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What you'll need:

TOOLS
  • Screwdriver
  • Garden hose
  • Prefilter
SUPPLIES
  • Sequestering agent
  • Start-up chemicals

The final step to jet-powered bliss is the filling. It’s not difficult, but following a few simple steps can ease the process and ensure you don’t end up with an air-locked system. Grab your garden hose, and keep reading to get your hot tub relax-ready. 

Prepping to Fill a Hot Tub

First, before putting a drop of water in your hot tub, ensure it’s in its permanent resting spot. Your hot tub isn’t going anywhere once filled. If you need to move it later, you’ll have to drain and refill it. Second, do not fill your hot tub unless you, if you have electrical experience or a pool electrician, have correctly connected the electrical system to a dedicated breaker. 

  1. Turn Off the Power to the Hot Tub

    Turn off the breaker to the hot tub. You don’t want to accidentally turn on the pump or heater and burn them up by running them dry. Turning off the electricity also eliminates the danger of shocks or electrocution. You won’t touch the power again until the hot tub is filled and ready to prime.

  2. Remove the Front Cabinet

    Using a screwdriver, remove the front cabinet that covers the control panel. The control panel houses the pump, heater, and sometimes key filtration system components. Check all the connections and couplings, especially those around the pump, to ensure they’re tight and secure. 

    Sometimes, these connections and fittings come loose during transport or when an electrician connects the hot tub. You can leave the front cabinet off while filling the tub, but put it back on if it takes more than a day. You don’t want animals or debris to get inside.

  3. Attach the Prefilter to the Garden Hose

    Attach the prefilter to the garden hose. The prefilter removes suspended solids to start conditioning the water. A prefilter alone won’t fully prepare the water for use, but it prevents hard water from entering your hot tub’s system.

  4. Remove the Hot Tub Filter Closest to the Control Panel

    Take out the hot tub filter that’s closest to the control panel. Keep in mind that not all hot tub designs are the same. Your filter may not be right next to the control panel. But choose one that’s near the pump and remove the filter. Put the filter at the bottom of the hot tub, where it can absorb water during the filling process. A wet filter starts working faster than a dry one.

  5. Place the Garden Hose End with the Prefilter On It Into the Filter Fitting

    A man filling up a hot tub with water from a hose
    Photo: Igor Vershinsky / iStock / Getty Images Plus / Getty Images

    Place the prefilter end of the garden hose end into the filter fitting. The water will enter the system through this fitting, though the prefilter doesn’t attach to the fitting. Make sure nothing else falls into the fitting while you’re filling. If something like a leaf or stick gets into the system, it can jam up the system before you even get a chance to enter the water.

  6. Turn on the Water

    Turn on the water. Check that the hose is still in place. Water pressure can sometimes displace the hose. You might need to adjust the water pressure at this point. If the water is sputtering, adjust the flow until it’s smooth. A smooth, consistent flow can prevent air from entering the system, causing an air lock.

  7. Add the Sequestering Agent

    Once the footwell is filled, pour the sequestering agent into the water as the hot tub fills. This agent further neutralizes suspended solids in the water. Read the instructions on the bottle to know how much to add. The sequestering agent should be the only chemical you add to the hot tub until after the water has fully cycled through the system after the priming cycle. After the priming cycle, you can adjust the chemical balance as indicated by the hot tub manufacturer's instructions.

  8. Let the Hot Tub Fill

    Continue to fill the hot tub until the water reaches the minimum water level indicated by the water fill line on the outside of the hot tub. The water level can go above this line and rise when people enter the water. But the water level should always stay above this line. Too little water can let air into the system, which can cause air lock.

  9. Turn Off the Water and Replace the Filter

    Once the water reaches the fill line, turn off the water and remove the hose from the hot tub. Take the filter out of the bottom of the hot tub and put it back in the fitting.

  10. Use the Bleeder Valve to Release Air (Optional)

    A professional loosening a hot tub valve
    Photo: welcomia / iStock / Getty Images Plus / Getty Images

    If your hot tub has a bleeder valve, loosen it until you hear air hissing. Leave it open until the hissing stops and water comes out. Close the valve. You don’t want to leave this valve open, as water will continue to come out.

  11. Turn the Power Back On

    Turn the breaker back on, and turn on the priming cycle. The priming cycle prepares the pump(s) and can take up to 40 minutes to complete. While the system is priming, check the connections, couplings, and fittings around the pump and heater one last time.

  12. Replace the Front Cabinet and Balance the Water

    Before replacing the front cabinet, make sure no debris or animals got into the control panel. After the water has cycled through once, you can add additional chemicals to treat and balance the water. You’ll still need to wait until the water reaches temperature, but you’re not far from enjoying your hot tub.

DIY vs. Hiring a Pro

Filling a hot tub doesn’t usually require a pro unless you’re short on time. In this case, you might be able to hire a local hot tub installer to fill it for you. You’re more likely to need a pro to connect the electrical system. While not all hot tubs require a dedicated breaker, in-ground hot tubs and large above-ground models with a heater and multiple pumps most definitely will. A local electrician can ensure everything is up to code and safely connected so you can soak up the hot tub’s benefits.

Frequently Asked Questions

You can fill your hot tub with a bucket, but it will take a long time, and the water won’t run through a prefilter. Look at it this way. If you need 700 gallons to fill the hot tub and you have a 5-gallon bucket, it will require 140 buckets to fill the hot tub.

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Learn more about our contributor
Stacey L. Nash
Written by Stacey L. Nash
Contributing Writer
Stacey has written in the home improvement space for more than five years for sites like The Spruce and Bob Vila. She’s written about everything from plungers to pavers, but her home improvement heart lies in finding the perfect textiles. She loves combining deep product research with in-person testing to help homeowners find the perfect tool, appliance, or solution for common home problems.
Stacey has written in the home improvement space for more than five years for sites like The Spruce and Bob Vila. She’s written about everything from plungers to pavers, but her home improvement heart lies in finding the perfect textiles. She loves combining deep product research with in-person testing to help homeowners find the perfect tool, appliance, or solution for common home problems.
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